Chlorinated paraffin waxes, particularly higher molecular weight solid or liquid chlorinated paraffins in the C.sub.10 to C.sub.30 range, have been widely used for over fifty years in metalworking, for example, as lubricant additives in drawing oils, extrusion oils and soluble oils, and particularly for extreme pressure applications. Chlorinated waxes are used almost exclusively in drawing oils, and chiefly in mineral oils. In extrusion oils, the additives usually include phosphorous and sulfur compounds due to the severity of operations. In soluble oils the chlorinated waxes are usually used in combination with fats or lard oils.
In 1977, twenty percent (40,000 tons)of the free-world production of liquid chlorinated paraffins was used in oil applications. However, in recent years, concern has arisen regarding toxicity and possible carcinogenicity of chlorinated paraffins. With the banning of chlorinated waxes in Germany and Canada, and the requirement of placing warning labels on drums of these materials in this country, alternative lubricant additives are being sought.
While many in the metalworking industry have switched to chlorinated olefins and polyesters to replace chlorinated paraffins, there is a concern among some that these chlorinated products may also have carcinogenic properties. Therefore, non-chlorinated substitutes are considered desirable. While sulfonated products have keen considered satisfactory for light machining applications, they have not been generally satisfactory for heavier machining, such as the severe metal cuts and draws for which use of the chlorinated paraffins has been favored.
In the past, a number of non-chlorine containing additives have been developed to provide lubricating oil compositions with enhanced friction characteristics for use in engine and machinery lubricating oils and fuels. Such additives have included phosphorous compounds such metal phosphonates, alkali metal salts of alkylphosphonic acids, and dihydrocarbyl hydrocarbylphosphonates; amines, such as alkoxylated amines; and certain boron-containing compounds. Examples of these prior art lubricating oil additives are discussed, for example, at column 1 of U.S. Pat. No. 4,529,528.
Published European Patent Application No. 152,677 discloses borated alkoxylated amines as thickeners for water-based functional fluids. Borated alkoxylated amines are also disclosed in U.S. Pat. Nos. 4,400,284; 4,427,560; 4,490,265; 4,533,480 and 4,557,843 of Union Oil Company as intermediates for extreme pressure, anti-wear additives in lubricating compositions.
A series of additives has also been developed by Mobil Oil Corporation which are reaction products (essentially mixtures of simple and complex esters) of organic amines and organic phosphonates or phosphites. Early examples of such compositions are disclosed in U.S. Pat. No. 3,553,131 of Hepplewhite et al., in which C.sub.6 -C.sub.40 diaryl phosphonates (phosphites) are reacted with primary, secondary, or tertiary organic amines to produce products or mixtures which are incorporated in ester lubricants which are alleged to have higher load-carrying properties, surprising stability under storage and are relatively non-corrosive to metals.
A more recent series of patents to Horodysky et al., assigned to Mobil, discloses engine lubricant and fuel additives which are the reaction product of a phosphorous compound, particularly a C.sub.1 -C.sub.6 dihydrocarbyl phosphite, with an alkoxylated amine or a vicinal diol, with or without a boron compound, such as boric oxide, a metaborate, boric acid, or an alkyl borate. See, for example U.S. Pat. Nos. 4,529,528; 4,557,845; 4,557,844; 4,555,353; 4,532,057 and 4,522,629. Mobil U.S. Patent No. 4,587,026 also discloses borated N,N-bis(2-hydroxpropyl)cocamine in the presence of dodecyl phenol sulfide as a friction-reducing, high temperature stabilizing additive.
While the reaction products of Hepplewhite and Horodysky, et al. are disclosed as possible additives for use with engine lubricating oils or greases, and as additives to liquid fuels such as gasoline, fuel oil and diesel oil, there is no disclosure of using these compounds for the severe requirements of metalworking fluid additives. Moreover, tests by the present inventors of several of the Horodysky et al. products have shown serious disadvantages in using such products as additives for metalworking fluids, particularly in extreme pressure (EP) applications.
U.S. Pat. No. 4,857,214 also discloses phosphorous-containing compounds useful as additives in lubricants. The compounds disclosed comprise the oil soluble reaction product of an inorganic phosphorous acid or anhydride, a boron compound and an ashless dispersant. The preferred acid is phosphorous acid. The ashless dispersant may be, e.g., a hydrocarbyl succinimide, a mixed ester/amide of hydrocarbyl-substituted succinic acid, hydroxyesters of hydrocarbyl-substituted succinic acid, and the Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde and polyamines. Additional sources of nitrogen such as N-tallow diethanolamine may also be used in combination with the ashless dispersant. However, there is no disclosure of using the reaction product of an alkanolamine, carboxylic acid and phosphorous acid as a metalworking lubricant additive.
U.S. Pat. No. 4,965,002 discloses lubricant additives useful for metalworking and extreme pressure applications produced by reacting an alkoxylated amine with a disubstituted organic phosphite. The additives preferably also contain a boron moiety which is reacted with the phosphite and the amine.
U.S. Pat. No. 5,130,036 discloses phosphorous amine lubricant additives for metalworking and extreme pressure applications produced by reacting an alkoxylated amine with phosphorous acid. The additives may also include a boron moiety, a mono-functional alcohol and/or a long-chain aliphatic carboxylic acid.